Evaluation of Antibacterial and Cytotoxicity Properties of Silver Nanowires and Their Composites with Carbon Nanotubes for Biomedical Applications

A new strategy to integrate silver nanowires with waterborne coating to improve their antimicrobial and antiviral properties

Purpose

This study aims to focus on the preparation and characterization of the silver nanowire (AgNWs), as well as their application as antimicrobial and antivirus activities either with incorporation on the waterborne coating formulation or on their own.

Design/methodology/approach

Prepared AgNWs are characterized by different analytical instruments, such as ultraviolet-visible spectroscope, scanning electron microscope and X-ray diffraction spectrometer. All the paint formulation's physical and mechanical qualities were tested using American Society for Testing and Materials, a worldwide standard test procedure. The biological activities of the prepared AgNWs and the waterborne coating based on AgNWs were investigated. And, their effects on pathogenic bacteria, antioxidants, antiviral activity and cytotoxicity were also investigated.

Findings

The obtained results of the physical and mechanical characteristics of the paint formulation demonstrated the formulations' greatest performance, as well as giving good scrub resistance and film durability. In the antimicrobial activity, the paint did not have any activity against bacterial pathogen, whereas the AgNWs and AgNWs with paint have similar activity against bacterial pathogen with inhibition zone range from 10 to 14 mm. The development of antioxidant and cytotoxicity activity of the paint incorporated with AgNWs were also observed. The cytopathic effects of herpes simplex virus type 1 (HSV-1) were reduced in all three investigated modes of action when compared to the positive control group (HSV-1-infected cells), suggesting that these compounds have promising antiviral activity against a wide range of viruses, including DNA and RNA viruses.

Originality/value

The new waterborne coating based on nanoparticles has the potential to be promising in the manufacturing and development of paints, allowing them to function to prevent the spread of microbial infection, which is exactly what the world requires at this time.

Potential Environmental and Health Implications from the Scaled-Up Production and Disposal of Nanomaterials Used in Biosensors

Biosensors often combine biological recognition elements with nanomaterials of varying compositions and dimensions to facilitate or enhance the operating mechanism of the device. While incorporating nanomaterials is beneficial to developing high-performance biosensors, at the stages of scale-up and disposal, it may lead to the unmanaged release of toxic nanomaterials. Here we attempt to foster connections between the domains of biosensors development and human and environmental toxicology to encourage a holistic approach to the development and scale-up of biosensors. We begin by exploring the toxicity of nanomaterials commonly used in biosensor design. From our analysis, we introduce five factors with a role in nanotoxicity that should be considered at the biosensor development stages to better manage toxicity. Finally, we contextualize the discussion by presenting the relevant stages and routes of exposure in the biosensor life cycle. Our review found little consensus on how the factors presented govern nanomaterial toxicity, especially in composite and alloyed nanomaterials. To bridge the current gap in understanding and mitigate the risks of uncontrolled nanomaterial release, we advocate for greater collaboration through a precautionary One Health approach to future development and a movement towards a circular approach to biosensor use and disposal.

Motion Detecting, Temperature Alarming, and Wireless Wearable Bioelectronics Based on Intrinsically Antibacterial Conductive Hydrogels

Hydrogels have attracted considerable interest in developing flexible bioelectronics such as wearable devices, brain-machine interface products, and health-monitoring sensors. However, these bioelectronics are always challenged by microbial contamination, which frequently reduces their service life and durability due to a lack of antibacterial property. Herein, we report a class of inherently antibacterial conductive hydrogels (ACGs) as bioelectronics for motion and temperature detection. The ACGs were composed of poly(N-isopropylacrylamide) (pNIPAM) and silver nanowires (AgNWs) via a two-step polymerization strategy, which increased the crosslink density for enhanced mechanical properties. The introduction of AgNWs improved the conductivity of ACGs and endowed them with excellent antibacterial activity against both Gram-positive and -negative bacteria. Meanwhile, pNIPAM existed in ACGs and exhibited a thermal responsive behavior, thereby inducing sharp changes in their conductivity around body temperature, which was successfully employed to assemble a temperature alarm. Moreover, ACG-based sensors exhibited excellent sensitivity (within a small strain of 5%) and the capability of capturing various motion signals (finger bending, elbow bending, and even throat vibrating). Benefiting from the superiority of ACG-based sensors, we further demonstrated a wearable wireless system for the remote control of a vehicle, which is expected to help disabled people in the future.

Fabrication of a Sensitive and Stable NiO Uric Acid Biosensor Using Ag Nanowires and Reduced Graphene Oxide

How to detect uric acid is an important issue. For the purpose of preparing a potentiometric uric acid biosensor, this research used nickel oxide (NiO) as the sensing film to deposit it onto the substrate by radio frequency sputtering, then modified it with reduced graphene oxide (rGO) and silver (Ag) nanowires. Reduced graphene oxide (rGO) not only has excellent electrical conductivity, but also can make the surface of the film have a larger surface area, while AgNWs have also been proven to improve catalytic activity; hence, these two materials were chosen as sensor modifiers. Finally, the stability and the various characteristics of the uric acid biosensor were investigated using a voltage–time (V–T) system. The results showed that the AgNW–uricase/rGO/NiO uric acid biosensor has average sensitivity with 4.66 mV/(mg/L). In addition, the sensor has good stability.

Enhanced Antibacterial and Anti-Biofilm Activities of Antimicrobial Peptides Modified Silver Nanoparticles

Background

The biofilms could protect bacteria from antibiotics and promote the production of drug-resistant strains, making the bacteria more difficult to be eradicated. Thus, we developed an AMP@PDA@AgNPs nanocomposite, which is formed by modifying silver nanoparticles (AgNPs) with antimicrobial peptides (AMP) modified nanocomposite to destroy biofilm in this study.

Methods

The AMP@PDA@AgNPs nanocomposite was prepared with polymerization method and characterized by using ultraviolet-visible (UV-vis) spectroscopy, dynamic light scattering (DLS), Fourier transform-infrared spectroscopy (FT-IR), and transmission electron microscope (TEM). The antibacterial effects of the nanocomposite were investigated by using agar diffusion method and minimum inhibitory concentration (MIC) test. The quantitative analysis of the biofilm formation by the nanocomposite was conducted using crystal violet staining and confocal laser scanning microscope (CLSM).

Results

The DLS and TEM analysis showed it was a spherical nanocomposite with 200 nm size and well dispersed . The results of UV-vis and FT-IR confirmed the presence of AMP and AgNPs. The nanocomposite had an excellent biocompatibility at 100 μg/mL. And the AMP@PDA@AgNPs nanocomposite showed superior antimicrobial activity against both Gram-negative (E. coli, P. aeruginosa) and Gram-positive (S. aureus) bacteria than AgNPs or AMP. Importantly, the mRNA expression of biofilm-related genes were decreased under the action of the nanocomposites.

Conclusion

An AMP@PDA@AgNPs nanocomposite with good biocompatibility was successfully prepared. The nanocomposite could destruct bacterial biofilms by inhibiting the expression of biofilm-related genes. The synergistic strategy of AMPs and AgNPs could provide a new perspective for the treatment of bacterial infection.

An in vitro selective inhibitory effect of silver(i) aminoacidates against bacteria and intestinal cell lines and elucidation of the mechanism of action by means of DNA binding properties, DNA cleavage and cell cycle arrest

Novel silver(i) aminoacidate complexes {[Ag(HVal)(H₂O)(NO₃)]}_n (AgVal) and {[Ag₃(HAsp)₂(NO₃)]}_n·nH₂O (AgAsp) were prepared, investigated and fully characterized by vibrational spectroscopy (mid-IR), elemental analysis, thermogravimetric analysis, X-ray crystallography and mass spectrometry. Their stability in D₂O and PBS buffer was verified by time-dependent ¹H and ¹³C NMR measurements. Their in vitro antibacterial activity (against pathogenic Staphylococcus aureus CCM4223, Escherichia coli CCM4787) and that against probiotic bacteria Lactobacillus plantarum CCM7102 and Lactobacillus reuteri (L26) were determined and potential dosing concentration was evaluated. The cytotoxicity of both the complexes against intestinal porcine epithelial (IPEC-1) and human epithelial colorectal adenocarcinoma (CaCo-2) cell lines was determined using the colorimetric MTT assay and against human metastatic melanoma (A2058), human pancreatic adenocarcinoma (PaTu 8902), human cervical adenocarcinoma (HeLa), human colorectal carcinoma (HCT116), human leukaemic T cell lymphoma (Jurkat), and human dermal fibroblasts (HDF) using colorimetric MTS assay. The selectivity index (SI) was identified for intestinal cancer (CaCo-2) and healthy (IPEC-1) cells. The mechanism of action of AgVal and AgAsp was further elucidated and discussed by the study of their binding affinity toward the CT DNA, the ability to cleave the supercoiled form of pUC19 DNA and the ability to influence numbers of cells within each cell cycle.